1. Field of the Invention
The present invention relates to a sheet of a polishing equipment and a method for making the same, and particularly to a sheet having discontinuous adhesion points and a method for making the same.
2. Description of the Related Art
Polishing generally refers to abrasion control of a rough surface in a chemical mechanical polishing (CMP) process. The polishing is performed by uniformly dispersing a slurry with fine particles on an upper surface of a polishing pad, and meanwhile repeatedly and regularly grinding a polishing workpiece held against the polishing pad. The polishing workpiece is an object such as a semiconductor, a storage media substrate, an integrated circuit (IC), an LCD flat glass, an optical glass, or a photoelectric panel. During the polishing process, a sheet is required to adsorb and fix the polishing workpiece, and thus the quality of the sheet may directly influence the polishing effect of the polishing workpiece.
FIG. 1 shows a schematic view of a type of polishing equipment having a conventional sheet. The polishing equipment 1 includes a pressure plate 11, a sheet 12, a polishing workpiece 13, a polishing plate 14, a polishing pad 15, and a slurry 16. The pressure plate 11 is opposite to the polishing plate 14. The sheet 12 is adhered onto the pressure plate 11 through a back-adhesive layer (not shown), and is used to adsorb and fix the polishing workpiece 13. The polishing pad 15 is fixed at the polishing plate 14 and faces the pressure plate 11, so as to perform polishing on the polishing workpiece 13.
The polishing equipment 1 operates as follows. First, the polishing workpiece 13 is placed on the sheet 12, and adsorbed by the sheet 12. Next, the polishing plate 14 and the pressure plate 11 rotate in opposite directions, and meanwhile the pressure plate 11 moves downward, such that the polishing pad 15 is in contact with a surface of the polishing workpiece 13. The slurry 16 is continuously supplied and the polishing pad 15 is employed to perform polishing on the polishing workpiece 13.
FIG. 2 shows a schematic enlarged view of the sheet in FIG. 1. The sheet 12 includes a buffer layer 121, an adsorption layer 122, and an adhesion layer 123. The buffer layer 121 is made of polyurethane (PU) resin and has a plurality of communicating pores. The adsorption layer 122 is also made of PU resin and is disposed on the buffer layer 121 to adsorb the polishing workpiece 13 (as shown in FIG. 1). The adhesion layer 123 is disposed between the buffer layer 121 and the adsorption layer 122. The adhesion layer 123 is made of a paste (for example, one-component PU resin) and completely fills the space between the adsorption layer 122 and the buffer layer 121, such that the adsorption layer 122 is adhered onto the buffer layer 121.
A disadvantage of the conventional sheet 12 is as follows. As the amount of the paste used to form the adhesion layer 123 may influence the adsorption force of the sheet 12, in the conventional sheet 12, the paste of the adhesion layer 123 completely fills the space between the adsorption layer 122 and the buffer layer 121, and thus the adsorption force of the sheet 12 is decreased. Consequently, water leakage may easily occur around the polishing workpiece 13 and the sheet 12 during the polishing process, so that the service life of the sheet 12 is shortened.
Therefore, it is necessary to provide a sheet having discontinuous adhesion points and a method for making the same to solve the above problems.